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RE: Load combinations with 30% Wind

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Harold, Bill

Thank you for your input.

Tarik BERAIR, PE,
CIVIL ENGINEERING DEPARTMENT
TECHNIP France
PARIS-LA-DEFENSE
Tel: +33-(0)1-40-90-11-13
Email: tberair(--nospam--at)technip.com





"Harold Sprague" <spraguehope(--nospam--at)hotmail.com>

05/09/2006 17:33
Please respond to seaint

       
        To:        seaint(--nospam--at)seaint.org
        cc:        
        Subject:        RE: Load combinations with 30% Wind



Tarik,
Various industries have had conventions regarding adjustments in wind
pressures or velocities that have seldom withstood scrutiny.  The proper way
of looking into this is to use a risk based study, but this is a lot of
work.  And it varies a lot with the type of structure within a petrochemical
facility.

You will find guidance in the Commentary of the ASCE 7.  Referring
specifically to the ASCE 7-05, you will need to reference C-6.5 beginning on
page 283.  It will reference Table's C6-6 and C6-7 on page 318.  You will
note that you can present the probabilities in a number of ways.  Most
people look at the mean recurrence interval for exposure over a given time
period.

I would recommend a lot of study in probabilities for environmental loads.  
It is easy to misinterpret.  Also bear in mind that what is being modified
are wind velocities not wind pressures.  Pressure varies with the square of
wind velocity.

You may also want to reference a paper by Boggs and Peterka, "Wind Speeds
for Design of Temporary Structures", ASCE Structures Congress 1992.

http://www.cppwind.com/papers/structural/temporarystructures.pdf


Regards,
Harold Sprague





>From: TBerair(--nospam--at)technip.com
>Reply-To: <seaint(--nospam--at)seaint.org>
>To: <seaint(--nospam--at)seaint.org>
>Subject: RE: Load combinations with 30% Wind
>Date: Tue, 5 Sep 2006 17:04:19 +0200
>
>Bill,
>
>I looked into ASCE-7, IBC, UBC-97 and even into "Wind Load and Achor Bolt
>Design for Petrochemical Facilities" which is an ASCE 1998 publication,
>but found nothing about the Testing, Maintenance or even Erection
>conditions.
>
>
>
>Tarik BERAIR, PE,
>CIVIL ENGINEERING DEPARTMENT
>TECHNIP France
>PARIS-LA-DEFENSE
>Tel: +33-(0)1-40-90-11-13
>Email: tberair(--nospam--at)technip.com
>
>
>
>
>
>
>
>"Scott, William N." <William.Scott(--nospam--at)veco.com>
>05/09/2006 16:53
>Please respond to seaint
>
>         To:     seaint(--nospam--at)seaint.org
>         cc:
>         Subject:        RE: Load combinations with 30% Wind
>
>
>Try American Society of Civil Engineers ASCE-7 2005.
>
>Bill
>
>
>From: TBerair(--nospam--at)technip.com [mailto:TBerair(--nospam--at)technip.com]
>Sent: Tuesday, September 05, 2006 6:28 AM
>To: seaint(--nospam--at)seaint.org
>Subject: Load combinations with 30% Wind
>
>
>Dear colleagues,
>
>We have been used to consider only 30% of the Wind when establishing load
>combinations for Abnormal Operating, Testing or Maintenance conditions (we
>design mainly downstream petrochemical facilities). I am investigating the
>origin of such an assumption in all US codes, but turned unsuccessful.
>Does anyone know a code that is mentioning this or any Load Combination
>for Testing or Maintenance?
>
>Regards
>
>Tarik BERAIR, PE,
>CIVIL ENGINEERING DEPARTMENT
>TECHNIP France
>PARIS-LA-DEFENSE
>Tel: +33-(0)1-40-90-11-13
>Email: tberair(--nospam--at)technip.com
>

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